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EQU INE INF LUENZA
Paul May BVMS MRCVS,
Paragon Veterinary Group
Understanding blood and
plasma transfusions
Blood and blood product transfusions are
readily available in equine practice, however
there are factors to take into account before
considering an appropriate product.
Transfusions are used to correct fluid loss which
may also involve protein and circulating blood
cell loss. The transfusion helps treat or prevent
shock and improves oxygen delivery to the
tissues thereby aiding recovery.
Whole blood transfusion
Indications:
●
Emergency use in severe bleeding, e.g.
from severe wounds or birth canal
damage at foaling.
●
Emergency use in a haemolytic (rupture or
destruction of red blood cells) crisis, e.g. in
autoimmune disease to provide support for
the patient to give time for other forms of
treatment to become effective.
●
Non emergency blood transfusions can be
used in chronic anaemia caused by, e.g.
gastrointestinal disease, or anaemia of
chronic disease where there is suppression
of the bone marrow by long term disease.
●
When the packed cell volume (volume % of
red blood cells in blood) falls below 12%
and or the horse’s haemoglobin falls below
8g/dl then a blood transfusion may be
considered. In general, the more rapid the
fall in these measurements, the more severe
the signs in the horse. It takes about four
days for the bone marrow to respond to an
increased need for production of blood cells;
the transfusion is aimed at supporting the
patient during that gap.
Blood groups
There are eight major blood groups in the horse
which are then further divided into sub-types. It
is important to identify the blood types and
cross match the donor with the recipient to
avoid groups that are most likely to cause a
reaction. Groups A,C and Q should be
avoided as donors, groups D,K,P and U are
considered safe for one transfusion.
Plasma transfusion
Indications:
●
Failure of transfer of immunity from mother to
foal (insufficient colostrum intake)
●
Septicaemia in foals
●
Protein loss from intestinal disease or surgery
●
Fluid imbalance in cases of excessive fluid
loss
●
Clotting deficiencies
Antibody specific plasma can be used in the
prevention and control of specific diseases such
as
Rhodococcus equi
, and in the treatment of
endotoxaemia that is associated with gut
disease or retained placenta in mares.
In foals, an IgG level of less than 8g/l would
merit considering a plasma transfusion. The
lower the level, the more important the plasma
transfusion becomes. Plasma can be prepared
from a suitable donor but the availability of a
commercially produced, quality product that is
free of blood cells and has a guaranteed
minimum protein level and in some cases, is
antibody specific, means that in practice this
is seldom done.
Technique for transfusion
The technique is very similar for blood and
plasma transfusions. If possible and timing
permits, any fluid deficit should be corrected
first. The horse should be restrained so that the
product can be administered with the least risk
of complications. Sedation may be considered
but care must be taken if shock is a component
of the condition. The area of the jugular vein
is clipped and cleaned on the recipient and
an intravenous catheter is inserted. The
transfusion is then delivered through an
appropriate giving set.
Whole blood should be used within four hours
of collection, frozen plasma should be carefully
thawed before use according to the
manufacturers instructions.
Once transfusion has begun, the delivery rate
should be slow for the first 10 minutes. If during
this time there are no complications, it is safe to
increase the flow rate. If complications are
encountered, the rate of delivery is slowed, any
supportive treatment is administered and if it is
considered safe, the transfusion is resumed.
Complications of transfusion
Whole blood transfusions can produce
reactions that may appear as agitation with
increased heart and respiratory rates, muscle
tremors, swellings in the skin and even collapse.
The horse is monitored during transfusion and
should these signs be noticed with cross
matched blood, appropriate action can be
effective if started soon enough.
Plasma transfusions tend not to induce reactions
but an increase in respiratory rate and shivering
may occasionally be seen. If that is the case,
slowing the rate of delivery is usually sufficient to
correct the signs.
Veterinary surgeon
Paul May
XLEquine practice
Paragon Veterinary
Group
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EQUINE MATTERS